The present invention relates to golf club heads. In particular, the present invention relates to a golf club head molded from a composite resin and having an integral web structure.
A golf club set generally includes xe2x80x9cironsxe2x80x9d and xe2x80x9cwoodsxe2x80x9d. The woods are the clubs that are generally used for longer distance shots. Of the woods, those that are generally used to achieve the longest shots are usually referred to as xe2x80x9cdriversxe2x80x9d.
Golf clubs have a golf club head at one end of a shaft and a grip at the other end of the shaft to allow a player to hold, position and swing the golf club.
Preferably, golf club heads should be manufactured to meet the requirements of a golfer for increased swing, reduced backspin on the ball and increased distance travelled by the ball. In order to fulfill these requirements a golf club head must be manufactured from a material that is strong enough to withstand the impact of the club with a golf ball at varying swing speeds yet also made from a lightweight material that enables a player to easily swing the club.
A golf club head should provide enough force on impact with a golf ball to enable the ball to travel a long distance. In order to provide the force a golf club head must have a particular mass. Golf club wood heads can have a mass in the range of 190-225 g. Typical golf club wood heads have a mass in the range of 200-225 g.
Traditional materials used to make golf clubs include woods, metals and ceramics. The metals that are commonly used include steel, aluminum alloy and titanium. Golf clubs have been traditionally made by casting or forging the golf club head from the material. Since the 1970s hollow metal golf club heads have been manufactured. One manufacturing method utilises a body and an interior mold core. The body is cast around the removable interior mold core and requires an opening within it in order to remove the mold core after casting. Once the interior mold has been removed the opening must be closed which involves attaching, usually by welding, a further piece of the club head over the opening. An alternate method involves the casting of two separate pieces of the head around interior molds, which are subsequently removed after casting. The two pieces are then joined together, usually by welding. Both these methods can be expensive and imperfections in the golf club head can arise from the welding processes.
The majority of clubs are manufactured using a process called xe2x80x9clost wax investment castingxe2x80x9d. This manufacturing method involves pouring molten metal into a mold to create the club head. Initially a mold has to be created into which the molten metal will be poured. A xe2x80x9cbrass masterxe2x80x9d is made using a combination of lathe, electro-etching, filing, sanding and grinding. The xe2x80x9cbrass masterxe2x80x9d is then placed in a cavity between two pieces of aluminum or steel to form an enclosed shell. Molten aluminum(xe2x80x9chard toolingxe2x80x9d) or molding resin (xe2x80x9csoft toolingxe2x80x9d) is then poured into the cavity to create a negative image. Once cooled the xe2x80x9cbrass masterxe2x80x9d is removed and only used again should another mold need to be created.
The next step in the process involves creating another duplicate of the head using wax injection. Wax is injected into the cavity of the mold to create a wax duplicate. After being checked for defects the wax duplicates are placed on a holder, also known as a xe2x80x9ctreexe2x80x9d. The holder and the heads are then coated in a ceramic slurry mix, and the coating is allowed to dry over time. This process is repeated until the heads have received several ceramic coats. Once dried the ceramic coatings commonly referred to as xe2x80x9cshellsxe2x80x9d are approximately xc2xcxe2x80x3 to xc2xdxe2x80x3 thick. The shells are then heated until the wax inside melts and a hollow ceramic shell remains.
The hollow shells are heated to temperatures in the range of 1,000xc2x0 C. and molten metal, at a temperature in the range of 1,500-1,800xc2x0 C., is poured into them. Once the metal has cooled, usually 24 hours later, the ceramic is removed from the heads. Initially the heads are repeatedly hit to remove the ceramic and then they are placed in a tumbling machine to remove the final pieces.
After the ceramic has been completely removed a further step is undertaken to grind the connection point (xe2x80x9cgatexe2x80x9d) on the head that held the head to the holder (xe2x80x9ctreexe2x80x9d)so that it is aligned with the contours of the head. The final steps in the process of manufacturing the heads using investment casting are to grind and polish or paint the club heads. Some heads are subsequently foam filled to achieve a greater club head weight, or to dampen any vibration and sound from the head hitting a golf ball, and catch foreign particles such as welding slag, sand, or ceramic.
Various metals can be used in the investment casting process including several types of steel, such as high nickel content steel, stainless steel and maraging steel. Titanium can also be used in investment casting. Titanium has a lighter weight then the alternate metals and has a higher strength to weight ratio however, Titanium casting must be performed in a vacuum environment.
Golf club heads manufactured from materials that are hard such as metals, generally do not easily absorb the energy that is translated through the club head when it hits a ball. This will cause the energy to resonate and travel up the shaft of the club to the golfer. When the club strikes the ball a significant amount of the energy may be lost through ball deformation or compression. Golf club heads manufactured from harder material may cause a higher degree of compression and therefore loss of energy which can decrease the velocity at which the ball leaves the club face and increase the spin on the ball. Golf club heads that are manufactured using traditional casting methods generally have a fixed centre of gravity. The location of the centre of gravity will depend on the density of the material and the size and shape of the golf club head.
Golf club heads have been manufactured incorporating a series of internal ribs within the head to reinforce the club head and minimise any structural changes that occur when the club head strikes a golf ball. The addition of internal structure within the golf club heads has increased the technical requirements for the traditional casting process.
Golf club heads have been manufactured from composite material incorporating one or more layers of a loaded film with a set of plies of pre-preg composite fiber sheet. The pre-preg composite fiber sheet is made by pulling strands of fiber, preferably copper or glass, through a resin film to produce a malleable sheet. The loaded film preferably contains a densifier, such as copper or iron, and/or a weighting agent distributed throughout the film. The golf club head is manufactured applying layers of the loaded film and the pre-preg sheet to a forming mold in a predetermined pattern, depending on the requirements of the club, to create a preform. The preform is then removed from the forming mold and further layers of the plies may be added to the exterior of the mold. The preform is then placed in a curing mold and cured for the required period of time. The structural characteristics of the golf club head, such as the weight and the center of gravity, can be defined by the type, dimensions, location and orientation of the plies in the preform. The majority of woods that are manufactured using this process are constructed from two or more pieces of preform and may require additional plies to be applied to the exterior of the joint areas to enhance the structural integrity of the club head. Metal materials may also be added in areas such as the sole for abrasion resistance and for shaft attachment and to enhance structural integrity.
It Is an object of the present invention to provide a durable lightweight golf club that reduces backspin and absorbs the shock from the ball impact without any structural deformity.
It is also an object of the present invention to provide a method of manufacturing a golf club head from a lightweight durable material that will minimise energy loss and ball compression upon striking a golf ball.
It is a further object of the present invention to provide a structurally rigid golf club made from a composite resin with an integral web design that is stronger than the traditional golf clubs an d allows energy to be transferred back to a golf ball upon contact of the golf club head with the ball.
It is a still further object of the present invention to provide a golf club head of a lightweight and durable material that readily allows for weighting to alter its inherent center of gravity.
A golf club head wit h a body having a ball striking zone with an outer face for contacting a golf ball and an interface. The body further has a web integral with the inner face of the striking zone to reinforce the striking zone.
The web may have a hub and a plurality of spokes radially extending from the hub. The golf club head is preferably made from a composite resin, formed by injection molding.
The body may have a front portion and a rear portion. The rear portion is joined to the front portion and the ball striking zone is located on the front portion opposite the rear portion.
A method is provided for making a golf club head. According to the method, a body of the club head is injection bolded in a body mold, from a suitable composite resin. The body is ejected from the body mold. Any fill spruce is removed from the body. The body is inserted in a cooling support and quenched.
Additionally, a rear portion of the club head may be injection molded in a rear portion mold, from a suitable composite resin. The rear portion is ejected from the rear portion mold and quenched. The rear portion and the front portion are joined to form the golf club head.